1. Field of the Invention
The present invention relates generally to a system for: (a) the sealing of a rocket launch tube prior to lift-off of the rocket contained in the launch tube, thus preventing the flow of exhaust gases into the tube area around the rocket itself; and (b) preventing the exaust gases from flowing around the rocket during the flyout of the rocket from the launch tube.
2. Description of the Prior Art
For military applications rockets, missiles, or other exhaust-gas propelled vehicles are often stored in closely adjacent magazines, chambers or launch tubes. In these cases, exhaust gas ducts are normally provided to convey rocket exhaust gases generated during rocket ignition to a safe location. Where available space is at a premium, as for example on board ship, manifolding of a number of closely adjacent launch tubes or chambers into a common exhaust manifold or plenum chamber is often necessary.
Various problems may develop if ducts connecting launch tubes to a common exhaust manifold are normally open before launch of the vehicles. If one or more of these rockets is intentionally or accidentally ignited, portions of the resulting exhaust gases, which may have temperatures as high as 6,000.degree. F., can be circulated through the common manifold, into the connecting ducts and into other launch chambers. This could ignite other rockets. Also, the warheads in the launch chambers could be detonated by these hot gases. At a minimum, the gases could damage the rocket, associated equipment and hold-down devices. Thus accidental or intentional ignition of one rocket could render a whole ship or launching system ineffective. In addition, if the some of the launch tubes are open at their upper ends, exhaust gases entering the chambers through the connecting ducts could escape through the open outer ends. This event could cause further heat or other damage.
To prevent such an occurrence, various types of safety doors and valves have been proposed in the past. These are normally installed either at the exhaust gas outlet of each launch chamber of in the connecting duct to the gas manifold. When the rocket is ignited, the associated safety door or valve is caused to open, usually in response to the exhaust gas. The result will be the admission of exhaust gases into the manifold or exhaust duct and into the area surrounding the rocket itself. The doors and valves associated with the system's launch tubes, containing rockets which are not being ignited, are normally maintained closed to prevent circulation of the exhaust gases. However, a malfunctioning door or valve could allow exhaust gases from one tube to enter the other launch tube.
Such doors and valves have been disclosed, for example, in U.S. Pat. No. 2,445,423 of Eastman which discloses a safety container for rockets. The disclosed hold-down doors consist of a one-way, two-flap check valve with associated springs to hold the flaps closed. The blast of exhaust gases from the ignition of the rocket blows the check valve open and actuates the system.
A second rocket exhaust control apparatus has been disclosed in applicant's prior U.S. Pat. No. 4,044,648. This patent discloses flow control doors which are hinged and provided with counterweights so that they are normally closed, but open under gas pressure after rocket ignition. The increased pressure in the exhaust duct will maintain the doors of the other launch chambers in the closed position and protect un-ignited rockets which are being stored.
Another type of rear door for rocket launch tubes is disclosed in applicant's prior U.S. Pat. No. 4,134,327. In this disclosure, the door is latched open and normally remains open until the rocket is launched. A protective seal or cover will normally close the launch tube until the missile is fired. After firing the door is released by, for example, a sensor as the missile leaves the launch tube. Gases from the launched rocket can also be used to power the door closed and a latch is provided to hook the door in place and seal off the launch tube from the associated plenum chamber after firing.
Still another apparatus for sealing launch tubes is disclosed in applicant's prior U.S. Pat. No. 4,186,647. In this case, a cover normally blocking the connection between the launch tube and the duct or plenum is provided. The cover has at least one frangible center section which is broken in response to the pressure and temperature of the exhaust of the exiting rocket. The breaking of the section opens a connection between the launch tube and the plenum. Thus, the system seals the tube from the plenum prior to firing but allows the escape of the rocket exhaust gases after ignition.
Further reference is made to Betts et al U.S. Pat. Nos. 3,968,646, 4,033,121 and 4,036,013. These patents disclose a rocket nozzle closure for controlling release of pressure. The nozzle is arranged in a manner which effects closing incrementally and continuously. As a result thereof, release of pressure is controlled by the rate of change of momentum of the system.